<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div id="app">
    <h2>{{message}}</h2>
    <h2>{{counter}}</h2>
    <!--    <button v-on:click="counter++">+</button>-->
    <!--    <button v-on:click="counter&#45;&#45;">-</button>-->
    <!--    <button v-on:click="increment()">+</button>-->
    <!--    <button v-on:click="decrement()">-</button>-->
    <button @click="increment()">+</button>
    <button @click="decrement()">-</button>
    <!-- 什么情况下方法后面需要加上括号？？？-->
    <!-- {{code}}显示"function () { [native code]}"-->
    <button @click="decrement">{{code()}}</button>
</div>
<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
<script>
    const app = new Vue({
        el: '#app',
        data: {
            message: 'simplelu',
            counter: 0
        },
        methods: {
            increment() {
                this.counter++;
            },
            decrement() {
                this.counter--;
            },
            code() {
                return '--'
            }
        }
    })
</script>
</body>
</html>